International Sunspot Number V2.0

DOI: https://doi.org/10.24414/qnza-ac80
Title: International Sunspot Number V2.0
Published: 2015
Publisher: Royal Observatory of Belgium (ROB)
Data Availability: https://www.sidc.be/SILSO/datafiles
Creators: Clette Frédéric, Lefèvre Laure
Contributors: SILSO team
Description: ----------------------------------------------------------------------------------------------------------------------------------
International Sunspot Number Description
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The International Sunspot Number computed by the World Data Center SILSO measures the number of spots and groups of spots on the surface of the Sun every day through a worldwide network of observing stations according to a formula developped by R. Wolf in 1851 (Wolf, R.: 1851, Sonnenflecken-Beobachtungen in der zweiten Hälfte des Jahres 1850. Mitt. Nat.forsch. Ges. Bern 207, 89.). Its first version was called the Zürich sunspot number series (or Sunspot Number version 1.0). In 2015, the historical series (version 1.0) was replaced by a new improved version (version 2.0) that includes several corrections of past inhomogeneities in the time series described in (Clette, F., Svalgaard, L., Vaquero, J.M., Cliver, E. W., 2014: Revisiting the Sunspot Number. A 400-Year Perspective on the Solar Cycle, Space Science Reviews, Volume 186, Issue 1-4, pp. 35-103. DOI: 10.1007/s11214-014-0074-2; Clette, F., Lefèvre, L., 2016, The New Sunspot Number: assembling all corrections, Solar Physics, 291, DOI: 10.1007/s11207-016-1014-y; Clette, F., Lefèvre, L., Cagnotti, M., Cortesi, S., Bulling, A., 2016: The Revised Brussels-Locarno Sunspot Number (1981 - 2015), Solar Physics, 291, DOI: 10.1007/s11207-016-0875-4 and Clette, F., Cliver, E.W., Lefèvre, L, Svalgaard, L., Vaquero, J.M., Leibacher, J.W., 2016: Preface to Topical Issue: Recalibration of the Sunspot Number, Solar Phys., 291, DOI: 10.1007/s11207-016-1017).
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Datasets description
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Daily total sunspot number (1818-now):
Daily total sunspot number derived by the formula: R= Ns + 10 * Ng, with Ns the number of spots and Ng the number of groups counted over the entire solar disk.
Files:SN_d_tot_V2.0.txt (column format), SN_d_tot_V2.0.csv (CSV format)
Contents: year, month, day, decimal year, SNvalue , SNerror, Nb observations,indicator
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Monthly mean total sunspot number (1749-now):
Monthly mean total sunspot number obtained by taking a simple arithmetic mean of the daily total sunspot number over all days of each calendar month.
Files :SN_m_tot_V2.0.txt (column format), SN_m_tot_V2.0.csv (CSV format)
Contents: year, month, decimal year, SNvalue , SNerror, Nb observations,indicator
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13-month smoothed monthly total sunspot number (1749-now):
The 13-month smoothed monthly sunspot number is derived by a "tapered-boxcar" running mean of monthly sunspot numbers over 13 months centered on the corresponding month (Smoothing function: equal weights = 1, except for first and last elements (-6 and +6 months) = 0.5, Normalization by 1/12 factor). There are no smoothed values for the first 6 months and last 6 months of the data series: columns 4, 5 and 6 are set to -1 (no data).
Files: SN_ms_tot_V2.0.txt (column format), SN_ms_tot_V2.0.csv (CSV format)
Contents: year, month, decimal year, SNvalue , SNerror, Nb observations,indicator
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Yearly mean total sunspot number (1700-now):
Yearly mean total sunspot number obtained by taking a simple arithmetic mean of the daily total sunspot number over all days of each year.
Files : SN_y_tot_V2.0.txt (column format), SN_y_tot_V2.0.csv (CSV format)
Contents: decimal year, SNvalue , SNerror, Nb observations,indicator
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Estimated international sunspot number (EISN) :
The estimated international sunspot number (EISN) is a daily value obtained by a simple average over available sunspot counts from prompt stations in the SILSO network. The raw values from each station are scaled using their mean annual k personal coefficient over the last elapsed year.
File : EISN_current.txt
Content : year, month, day, decimal year, estimated SN , estimated error, nb stat used, nb stat available,indicator
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Daily hemispheric sunspot number (1992-now):
Daily total and hemispheric sunspot numbers derived by the formula: R= Ns + 10 * Ng, with Ns the number of spots and Ng the number of groups counted either over the entire solar disk (total), the North hemisphere or South hemisphere (based on the sunspot group heliographic latitude).
Files: SN_d_hem_V2.0.txt (column format), SN_d_hem_V2.0.csv (CSV format)
Contents: year, month, day, decimal year, SNvalue(tot), SNvalue(N), SNvalue(S), SNerror(tot), SNerror(N), SNerror(S), Nb observations,indicator
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Monthly mean hemispheric sunspot number (1992-now):
Monthly mean North/South sunspot numbers obtained by taking a simple arithmetic mean of the daily North/South sunspot numbers over all days of each calendar month. Each sunspot group is counted in one of the hemispheres based on its heliographic latitude.
Files : SN_m_hem_V2.0.txt (column format), SN_m_hem_V2.0.csv (CSV format)
Contents: year, month, decimal year, SNvalue(tot), SNvalue(N), SNvalue(S), SNerror(tot), SNerror(N), SNerror(S), Nb observations,indicator
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13-month smoothed monthly hemispheric sunspot number (1992-now):
Monthly smoothed mean total and North/South sunspot numbers. The 13-month smoothed monthly sunspot numbers are derived by a "tapered-boxcar" running mean of monthly hemispheric sunspot numbers over 13 months centered on the corresponding month (Smoothing function: equal weights = 1, except for first and last elements (-6 and +6 months) = 0.5, Normalization by 1/12 factor).
Files: SN_ms_hem_V2.0.txt (column format), SN_ms_hem_V2.0.csv (CSV format)
Contents: year, month, decimal year, SNvalue(tot), SNvalue(N), SNvalue(S), SNerror(tot), SNerror(N), SNerror(S), Nb observations,indicator
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Documentation : The production of version 1.0 is described in Clette, F., Berghmans, D., Vanlommel, P., Van der Linden, R.A.M., Koeckelenbergh, A., and Wauters, L.: 2007, Advances in Space Research, 40, 919. doi:10.1016/j.asr.2006.12.045.
While the recalibration leading to version 2.0 is described in:
1. Clette, F., Svalgaard, L., Vaquero, J.M., Cliver, E. W., 2014: Revisiting the Sunspot Number. A 400-Year Perspective on the Solar Cycle, Space Science Reviews, Volume 186, Issue 1-4, pp. 35-103. DOI: 10.1007/s11214-014-0074-2;
2. Clette, F., Lefèvre, L., 2016, The New Sunspot Number: assembling all corrections, Solar Physics, 291, DOI: 10.1007/s11207-016-1014-y;
3. Clette, F., Lefèvre, L., Cagnotti, M., Cortesi, S., Bulling, A., 2016: The Revised Brussels-Locarno Sunspot Number (1981 - 2015), Solar Physics, 291, DOI: 10.1007/s11207-016-0875-4;
4. Clette, F., Cliver, E.W., Lefèvre, L, Svalgaard, L., Vaquero, J.M., Leibacher, J.W., 2016: Preface to Topical Issue: Recalibration of the Sunspot Number, Solar Phys., 291, DOI: 10.1007/s11207-016-1017;
Dates: [2015, open]
Data Citation: Scientific papers using SILSO Sunspot Numbers are asked to
(1) notify us
(2) cite the current DOI: The following latex/bibtex bibitem is suggested:
@misc{SILSO_Sunspot_Number,
  author = {{Clette}, F. and {Lefèvre}, L.},
  title = {SILSO Sunspot Number V2.0},
  howpublished = {https://doi.org/10.24414/qnza-ac80},
  month = {07},
  year = {2015},
  note = {Published by WDC SILSO - Royal Observatory of Belgium (ROB)}
}
Resource Type: Dataset
License: CC BY NC 4.0, https://creativecommons.org/licenses/by-nc/4.0/